Patent GB-762525-A (GB)
Title: Machine for injection moulding of plastic articles
IPC: B29C45/06
Filed: 1954-04-22
Abstract: 762,525. Injection-moulding machines. SPECIALITES ALIMENTAIRES BOURGUIGNONNES. April 22, 1954 [Feb. 1, 1954], No. 11712/54. Class 87(2). [Also in Group XXIV] An injection-moulding machine of the rotarymould-table type includes water-cooled sprueforming plates 31, Fig. 6, one plate being associated with each mould. In the injection position shown in Fig. 6, such a plate is clamped between the injection cylinder 51 and an upper mould part 29, an orifice 75 in the plate being aligned with the injection nozzle 76 and a sprue passage 77 in 29. After injection the mould and plate descend and move away from the injection cylinder, and the article 81 cools in the mould. Then the plate is lifted off part 29 to expose the sprue head S, Figs. 12 and 21, which is formed in passage 75 during injection, the head remaining attached to the sprue in part 29 (this lifting off being possible because the passage tapers upwardly). Part 29 is then lifted off the moulded article, which remains anchored to the lower mould part 28 by undercuts in the latter, the sprue in passages 75 and 77 breaking away from the article (see Fig. 21). Then pincer-like jaws 93, 94, Figs. 12 and 13, grip the sprue and throw it aside. A table 24, Figs. 1 and 2, is rotated intermittently by electric motor 7 and Geneva mechanism 21, 22. The table carries eight moulds and rotates in 45 degrees steps, each mould in turn being stopped at each of eight stations I .... VIII. At I material is injected into the mould. From II to V the material cools in the mould. At V the plate 31 is lifted and moved aside. At VI the upper mould part is lifted off and the sprue removed. At VII the article is ejected and removed. At VIII the mould parts and plate 31 are reassembled. At I material is fed from a hopper 60, Fig. 5, by a slide 61 into the injection cylinder 51 where it is tamped down by a piston 62. At the lower end of the cylinder the material is ejected through nozzle 76 by a piston 52, Fig. 2, secured to a rod 53 passing through piston 62. As piston 62 descends, piston 52 rises, and vice versa. Piston 62 is reciprocated by a crank 17 on shaft 13 through rod 57, lever 63 and spring connection 66, 66a. Piston 52 is reciprocated by rod 57 through lever 54 and link 56. The feeding (leftward) stroke of slide 61 is effected by descent of piston 62, by way of collar 67, lever 68 and rod 61a. A spring 61b retracts the slide. Within the nozzle is an obturating valve slide 69, Fig. 19, which is forced to the open (leftward) position, Fig. 6, by pressure of the material through a by-pass 79 and is later closed (during descent of piston 62) by a cam 71 acting on rod 57 (see Specification 762,509). The moulds shown are for making packings for use in capping bottles, flasks &c. Each mould comprises the lower and upper parts 28, 29, and an article-ejecting plunger 80. Each part 28 is secured to a carrier 25 vertically slidable in a bore in table 24, and is raised to the mould-filling position of Fig. 6 by a cam 14 on shaft 13, the cam acting, Fig. 4, through lever 46, link 47, toggle 48, 49 and push-rod 50. When the rod 50 drops, the mould parts drop away from the injection cylinder to the Fig. 4 position. Each part 29 is secured to a plate 30, Fig. 12, carried by two rods 27 joined by a plate 271, and is raised by a cam 16 acting through lever 85, rod 86 and plate 89. The parts 28, 29 are lowered by gravity with or without springs. Each plate 31 is pivotally secured to the top of a rod 177, Fig. 9, urged downwardly by a spring 175 but raised at intervals by an arm 178, Fig. 2. The mould parts 28, 29 are plate 31 are water-cooled, the water supply being through a manifold 34 that rotates with the table and pipes 32, 33. When a mould has been filled at station I it descends, with its plate 31, to the Fig. 4 position and moves in steps to station V. At station V the plate is raised by arm 178 and is swung aside to the Fig. 7 position by a spring 184, the rear end E of the plate resting on a step 182 on plate 30. At station VI the cam 16 raises the upper mould part 29, via rod 86, breaking the sprue away from the article. The upward movement of rod 86 raises arm 178 via collar 88, Fig. 12, to raise a plate 31 at station V, and the upward movement of plate 89 turns a shaft 91 through 180 degrees by means of a pin and cam connection 97 (see Group XXIV). Shaft 91 carries at its top two pairs of jaws 93, 94, Fig. 13, jaws 93 being fixed and jaws 94 being pivotable and joined by spring 96. At the end of the turning movement of shaft 91 the left-hand pair of jaws, which are kept open during the turning movement by a leaf spring 105a, is brought to the sprue-engaging position shown, and when the ascending mould plate 30 strikes a pin 107 the spring 105a is released and the jaws close on the sprue head. Plate 30 then descends, leaving the sprue in the jaws. Also, at the end of the turning movement the right-hand pair of jaws, carrying a previously-removed sprue, is opened by a fixed cam 105 and the sprue is flung away. Both jaws may be pivotable and inter-geared (Fig. 15, not shown). From station VI to station VII the upper mould part is kept in its raised position (to allow ejection of the article from the lower mould part) by riding on a raised step 111, Figs. 9 and 13. At station VII cam 15, Fig. 2, lifts a rod 121, Fig. 9, to raise the ejector 80 and article 81 to the dottedline position shown, whereupon a cam 129, rising with rod 121, releases a detent 127 and allows a spring-urged slotted article-supporting blade 123, Figs. 7 and 9, which has previously been held in the retracted position shown in Fig. 7, to rock clockwise about pivot 125 and position itself below the article. Ejector 80 descends, laying the article on the blade, a finger 133 on shaft 125 is rocked by a projection 132 on an advancing lower mould carrier 25, and the blade is thus rocked counterclockwise, the article being whirled into a receptacle. Between station VII and VIII the upper mould part descends along a ramp 111a to the closed position shown in Fig. 6. As the upper mould part moves along step 111 a catch 111a carried thereby rocks shaft 177 and hence plate 31 to the mould-aligned position shown in Fig. 9, one end of the plate falling off step 182, Fig. 7, and being locked in the aligned position, and the rotation of cams 15 and 16 restores the parts to the Fig. 6 position. Each mould may have four cavities.